QNetworkCookie: Use RFC6265 rules for parsing Set-Cookie

QNetworkCookie: Use RFC6265 rules for parsing Set-Cookie

The ';' separator takes priority even inside a quoted string.
Quotation marks have no special meaning, they are not parsed and
regenerated anymore. This means it is not possible to include
the ';' character inside a cookie value.
Other characters are returned transparently, including [",\]

Task-number: QTBUG-15794
Task-number: QTBUG-26002
Task-number: QTBUG-11641
Change-Id: I4eefef5c6ac7753d5a21c226169e264578521fe9
Reviewed-by: Richard J. Moore <rich@kde.org>